Optimizing loop-type cryogenic modulation in comprehensive two-dimensional gas chromatography using time-variable combination of the dual-stage jets for analysis of crude oil.

•Modulation plays the central role to enhance the analytical performance in GC×GC.•Loop-type cryogenic modulators are commonly used in GC×GC analysis of crude oil.•Tuning the dual-stage jets in GC×GC is difficult for complex samples like crude oil.•A time-variable combination of the dual-stage jets is proposed to handle modulation.•DoE was used to optimize the setting of the dual-stage jets along the GC×GC analysis.